The subject matter of the present invention relates to a method and apparatus for simultaneously initiating the detonation of a plurality of shaped charges in a perforating gun adapted to be disposed in a wellbore. The perforating gun includes an electrical current carrying conductor, a current pulse generator connected to the conductor, a plurality of shaped charges, and a plurality of exploding foil or exploding bridgewire initiators connected, respectively, between the plurality of charges and the current carrying conductor for simultaneously detonating the charges in response to a pulse of current from the current pulse generator. Exploding bridge wire initiators and exploding foil initiators are known in the art. For example, U.S. Pat. No. 3,181,463 to Morgan et al discloses an exploding bridge wire detonator. In addition, U.S. Pat. No. 5,088,413 to Huber et al, assigned to the same assignee as that of the present invention, entitled "Method and Apparatus for Safe Transport Handling Arming and Firing of Perforating Guns using a Bubble Activated Detonator" discloses an exploding foil "bubble activated" initiator which utilizes a bubble instead of a flying plate to detonate an explosive charge, In addition, prior application Ser. No. 08/116,082, filed Sep. 1, 1993, now U.S. Pat. No. 5,347,929, entitled "Firing System for a Perforating Gun including an Exploding Foil Initiator and an Outer Housing for conducting Wireline current and EFI current", assigned to the same assignee as that of the present invention, discloses a firing head, utilizing an exploding foil flying plate or the bubble activated initiator of the Huber et al patent, for use in a perforating gun. In addition, exploding foil "flying plate" initiators are known in the art. For example, U.S. Pat. No. 4,788,913 to Stroud et al, entitled "Flying Plate Detonator using a High Density High Explosive" discloses an exploding foil flying plate initiator. The flying plate initiator has been disclosed in connection with a perforating gun in U.S. Pat. No. 4,762,067 to Barker et al, entitled "Downhole Perforating Method and Apparatus using Secondary Explosive Detonators". However, the exploding foil "flying plate" initiator in the Barker et al patent patent initiates a detonation wave in a detonating cord, and the detonation wave in the detonating cord subsequently detonates a plurality of charges in the perforating gun.
Instead of using a conventional detonation wave to detonate a plurality of shaped charges in a perforating gun, it would be desirable to use an electrical current pulse generator to flow a pulse of current in an electrical current carrying conductor and to use that pulse of current to detonate a plurality of shaped charges in a perforating gun.
U.S. Pat. No. 5,094,167 to Hendley, Jr uses an ordinary current conducting in an electrical conductor to detonate a plurality of shaped charges in a perforating gun. Each of the shaped charges in the Hendley patent include an initiator known as a semiconductor bridge initiator. Although the semiconductor bridge initiator is useful for some purposes, it would be more desirable to use a plurality of exploding foil or exploding bridgewire initiators, in lieu of the semiconductor bridge initiator, to detonate a respective plurality of shaped charges-in a perforating gun. None of the shaped charges in the Hendley patent utilize an exploding bridgewire initiator or an exploding foil flying plate or bubble activated initiator (EFI initiator).
U.S. Pat. No. 4,658,900 to Stout entitled "High Energy Firing Head for Well Perforating Guns" discloses a single shaped charge which includes a flying plate initiator. This single shaped charge is pointing downwardly in a perforating gun, and the jet from the shaped charge initiates a detonation wave in a detonating cord. However, since the detonating cord is connected to the plurality of shaped charges, the shaped charges are detonated by the detonation wave in the detonating cord, not by an electrical current flowing in an electrical current conductor.
In addition, recall that, in addition to a plurality of shaped charges and a corresponding plurality of initiators, a current pulse generator is also connected to the electrical current carrying conductor. The current pulse generator could comprise a prior art charging circuit including a large capacitor charged by a charging current from a high voltage source, or a prior art compressed magnetic flux (CMF) generator. The prior art CMF generator is described in an article entitled "Small Helical Flux Compression Amplifiers" by J. E. Gover, O. M. Stuetzer, and J. L. Johnson, Sandia Laboratories, Albuquerque, N. Mex., printed in "Megagauss Physics and Technology", 1979. The CMF generator is also described in an article entitled "The Central Power Supply", Showcase for Technology, conference and exposition, 1981.
Therefore, it would be desirable to provide a new perforating system adapted to be disposed in a wellbore which propagates a current pulse from a current pulse generator through an electrical current carrying conductor to a plurality of initiators corresponding, respectively, to a plurality of shaped charges of the perforating system, and to use that current pulse to simultaneously detonate the plurality of initiators and the plurality of shaped charges of the perforating system.
In addition, it would be further desirable to provide a new preferred design for a shaped charge adapted for use in connection with the new perforating system.
It would be further desirable to provide a new preferred design for an electrical current carrying conductor adapted for use in connection with the new shaped charge in the new perforating system.
It would be further desirable to provide a new preferred design for a current pulse generator adapted for use in connection with the new current carrying conductor in the new perforating system.